I'm not a network person at all. Even thinking about connecting electronic devices together so that they can communicate with each other gives me panic attacks...

I recently purchased a Blu-Ray DVD player (Panasonic DMP-BDT210 Integrated-Wi-Fi 3D Blu-ray DVD Player) that supports streaming Netflix and something called "Viera Cast". I also have an older (late 2007 vintage) Xbox 360, but have never connected it to the Xbox 360 Live service, however now there is some downloadable content to a game I'm playing that I'd like to get.

Both the Blu-Ray player and the Xbox 360 are in my basement rec room, hooked up to an older (2005) HDTV. Also connected to the TV is a digital cable box (Motorola DCX3400-M) that Comcast provided.

Two floors up, in my office, I have an Arris WBM760 cable modem (also supplied by Comcast) connected to my PC. I have a currently unused Belkin Wireless G router (model F5D7230-4, ver.8000) that my ex-girlfriend once set up for me before I moved to a new place because she was often over and wanted to access the internet on her laptop. She put some convoluted password on it that I don't think I could ever figure out, but it has some wired ethernet ports on the back also. Setting up a wireless network is too daunting for my limited skills so I am okay going with a wired setup right now.

So, what I want to do is get the digital cable TV box, Xbox 360 and Blu-Ray player all connected to the internet simultaneously. How do I do that? Should I get another cable modem and then use the Belkin router to connect the Blu-Ray player and the Xbox 360? What about the digital cable TV box? Would a coaxial cable splitter upstream of the cable modem work? Everything I am reading about cable modems and routers seems to imply that a computer (PC) needs to be connected somewhere in the setup, but there wouldn't be one there!

I thought this would be easy to figure out online, but the more I read, the more confused I become!

Assuming I've parsed everything you've said correctly, your situation is relatively simple. I'm not sure what you mean by not having a PC anywhere in the setup, since presumably you still want your computer to have internet access, so I'll assume you'll be connecting that too.

A router is a piece of equipment that splits a single internet connection among multiple devices. You could go wireless, but you've said you're fine with going wired. That's probably for the best, since you'd have to buy wireless adapters for the Xbox and DVR, and wireless tends to be unreliable for gaming at that distance anyway. Luckily, the only complicated part of setting up a wired network is routing the cables. From a connection standpoint, it's cake:

1. There are five ethernet ports on the back of your router; four grouped together (labeled 1-4), and one set apart, probably labeled "Modem". Connect the ethernet cable from the modem to the "modem" port.

2. Connect your computer, Xbox, DVR, and Blu-Ray player to the other four ports. It's probably best to connect your computer to port 1, but it probably doesn't matter. I'll leave the logistics of running 3 ethernet cords down two floors up to you.

That's it, with the caveat that you'll probably have to re-register your modem with Comcast, following the same procedure you did when you originally set up your service. However, since you say this modem's been used in the past, you might not have to. So try to get on the internet with your computer and see what happens. I don't have Comcast, so I don't know exactly how they deal with this kind of thing.

I'll just add that if you want to just run one wire from your office down to your TV area you can use a switch. Plug that one wire into the switch and it will provide (usually 4 or more) more ports that you can connect to your components.

Is there no alternative to connecting my PC to the router and running one or more ethernet cables down two flights of stairs or going wireless? In other words, does a computer have to be connected to a router and/or cable modem for them to work?

Lets clear up a few misconceptions first:
1) The Cable Modem is where your internet "comes from". You only ever have ONE of these. But it can generally be put anywhere you have a Coax cable coming straight from the box on the side of your house (ie with not too many extra splitters other than the one in the outside box in between reducing the signal)
2) A Router is a device to SHARE your internet among different devices. All devices that you want to use the internet on HAVE to be connected to the router either by a wire or by wireless to have the internet. When using a router your cable modem connects to the router directly, and not to any computers or other devices.
3) To get internet to your devices you either have to run a wire to the router, or use wireless.
In your situation if there is already a coax cable running downstairs, it may be easiest to move the cable modem and router downstairs, connect each downstairs device with an ethernet cable, and buy a wireless usb card for your main PC upstairs to connect it.

Just an FYI: your Xbox 360 doesn't have wireless capabilities right now, and getting an adapter will cost you about $90 (there are ways to hack an older router, but I'm guessing that's out of the equation).

Anyone have any information about the adapters that plug into your house's electrical current?

Also with the Xbox 360, there are devices called wireless "Gaming adapters" that connect via the ethernet port on an old xbox 360 and convert to wireless - they are somewhat cheaper than the official wireless adapter which has always been absurdly overpriced. IE for example, this one for $42 - http://www.amazon.com/TRENDnet-Wirel...9273654&sr=8-1

These aren't really xbox specific - they can connect anything with an ethernet port only to wireless. Similar concept to the hacked router spoken about above, but without hacking needed.

I've done a little more research, now that I have a bit better grasp of the vocabulary (thanks!)...powerline adapter kits seem to get generally good reviews as a more reliable alternative to wireless connections when hard wiring with CAT5 cable is impracticable. Something like this. It appears that this would only be sufficient to connect one device on the far outlet, but powerline adapter switches also exist. Does anyone have experience with this approach? I really don't want to be running wires all over my house!